Browsing by Author "Rasquin, Priscilla."
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Comparative studies in the light sensitivity of blind characins from a series of Mexican caves. Bulletin of the AMNH ; v. 89, article 5(New York : [American Museum of Natural History], 1947) Breder, Charles M. (Charles Marcus), 1897-; Rasquin, Priscilla."One. Five caves in a Mexican valley in the state of San Luis Potosi contain related blind characins differing slightly in morphology and reactivity to light. 2. The deriving river form and the blind cave forms still somewhat pigmented near the river connection are light negative, while the unpigmented are light positive. 3. The unpigmented forms in the cave nearest the river became light negative after having been kept in light for a time, concomitantly developing a heavy layer of guanine, and some of those from the next cave in a similar manner developed melanophores, while those from the remaining three caves showed no such changes in behavior or pigmentation following exposure to light. 4. The phototaxis exhibited, either positive or negative, is mediated through the remnant optic cyst, since both types become light indifferent on removal of the cysts. However, some fish in all the more advanced populations are light indifferent and have no nervous connection between the cyst and the brain. 5. The sign of the phototaxis is determined by whether the pineal complex is exposed to light or not, the fish in which it is exposed being light positive. Thus with the elimination of pigmentation and the reduction of other overlying tissues, these fishes, in an evolutionary sense, pass from a condition of being light negative to that of being light positive. 6. The sign of the light reaction may be reversed experimentally by covering the normally exposed pineal area or exposing the normally covered area in the two types of fishes. 7. Hybrids between light positive and light negative fishes are found to be intermediate in morphology and reactivity to light. 8. All these fishes have a secondary 'pineal opening,' which is well covered with pigment and guanine in the river fish and the less advanced cave forms. However, these structures are progressively reduced in the more advanced cave forms, thus accounting for the exposed area. 9. Genetic and morphologic data suggest that these populations worked up the now dry valley under ground and did not simply 'sink' into the ground from local surface populations when the caves were formed to develop independent but parallel blind fish populations. 10. The survival value of a light negative reaction of blind fishes near a cave outlet is obvious, and it would appear that the reversal of sign in the more advanced forms can be tolerated only because it occurs in caves too remote from surface outlets to permit the fishes from draining out into an unsuitable lighted environment"--P. 349.Item Endocrine imbalance and tissue hyperplasia in teleosts maintained in darkness. Bulletin of the AMNH ; v. 104, article 4(New York : [American Museum of Natural History], 1954) Rasquin, Priscilla.; Rosenbloom, Libby.Item The influence of light and darkness on thyroid and pituitary activity of the characin Astyanax mexicanus and its cave derivatives. Bulletin of the AMNH ; v. 93, article 7(New York : [American Museum of Natural History], 1949) Rasquin, Priscilla."One. The eyed, river-dwelling characin, Astyanax mexicanus, can live for apparently indefinite periods in total darkness, but under such conditions develops hyperplasia of the thyroid, reduction in the relative number of pituitary basophiles, reduction in the size of the gonads, and an alteration in body form caused by the accumulation of subdermal fat. 2. The blind, cave-dwelling derivatives of Astyanax thrive in either light or darkness, and under either condition show no reduction in size of the gonads nor any change in body form. The form from La Cueva Chica may exhibit a slightly increased thyroid activity in the light, and deposits additional quantities of subdermal guanin. The form from Cueva de los Sabinos shows neither of these reactions. 3. When either river or cave fish that have been raised in the light are placed in darkness, no reduction in guanin takes place. 4. For comparison, young Ameiurus were similarly treated and showed a slight rise in thyroid activity in darkness. 5. Blinded river fish kept in the light show no morphological changes like those exhibited by individuals kept in the dark. Therefore enforced activity caused by the impossibility of optical fixation in the river fish in the dark cannot be the cause of increased thyroid activity, since the blinded fish kept in the light are forced into the same activity without subsequent increase in the height of the thyroid epithelium. 6. Hyperplasia of the thyroid in the normal river fish in light may be produced by treatment with thiourea, and a decrease in thyroid activity in river fish kept in the dark may be produced by feeding desiccated mammalian thyroid. In the first case the condition approximates that found in the untreated fish living in the dark, and in the latter the decrease may exceed that of normal fish living in the light. 7. The development of aberrant features in river fish kept in the dark and the lack of these features in their cave-dwelling derivatives may indicate that the latter have developed some modification of the endocrine system that enables them to function normally in the total darkness of caves. 8. Because of these reactions of the river fish to a totally dark environment, the present extensive cave populations may have been established by a few fish from the river that were able to make the appropriate endocrine adjustment, or from the eggs of river fish spawned in the cave before the influence of darkness had disturbed the endocrine balance sufficiently to make reproduction impossible. None of the present experimental animals was able to make such an adjustment. The physiological behavior of fish produced from eggs hatched in darkness is yet to be determined"--P. 528.Item Ovarian morphology and early embryology of the pediculate fishes Antennarius and Histrio. Bulletin of the AMNH ; v. 114, article 4(New York : [American Museum of Natural History], 1958) Rasquin, Priscilla."The histo-morphology of the ovaries of the pediculates Histrio histrio, Antennarius scaber, and Ogcocephalus vespertilio is described. 2. The ovaries of all three species show similar characteristics: fusion of the two glands at their caudal ends, presence of ovigerous tissue on one side of the lumen only, and considerable quantities of smooth muscle in the walls. 3. The ovaries of Histrio and Antennarius consist of flattened sacs scrolled from the distal lateral tips ventrally towards the midline of fusion; the ovary of Ogcocephalus is scrolled along the longitudinal axis of each ovary, the long edges of the organ rolled ventrally. 4. The structure of the egg raft of Histrio is described. The mucoid material in which the ova are embedded is secreted by the epithelium lining the ovarian walls and covering the lamellae. At ovulation, the mucoid material is cast into the lumen along with the ova which have ruptured from the follicles. The form of the raft is a replica of the internal surfaces of the ovary. 5. Pores in the raft are formed by spaces caused by the junction of lamellae with the ovarian wall where no mucus-producing epithelium is present. When the raft is released, sea water enters the pores, presumably carrying sperm with it. Each ovum is then confined in its own mucoid-walled compartment, free to revolve in the sea water contained within the compartment. 6. The frequency of raft release by mature female Histrio was found to vary between once every three days and intervals of several weeks. 7. The explosive character of the release of the raft is discussed. The central portion of the raft, from the fused part of the ovary immediately above the oviduct, issues from the vent first, followed by the portion from one side of the ovary, followed in turn by the portion from the remaining side. The ovulation takes many hours to complete; the final release is affected by pressure of the mass within the ovary, contractions of the muscular ovarian wall, and contractions of the abdominal muscles. 8. A detailed description of the early embryology of Antennarius is given, with a short comparison with Histrio development. Development of these pelagic larvae shows several deviations from the classic pattern of vertebrate embryology. Up to the time of their death, nine days after having been spawned, the following features were noted to be lacking: vitelline circulation, hemoglobin and blood cells, and nephric tubules. No division of somites into somatopleure and splanchnopleure could be identified. No true proctodeum or stromadeum is developed, as there is no invagination of outside ectoderm in these areas. A simple slit appears in the outer covering. The yolk is absorbed by the liver. 9. The larvae possess large subdermal spaces and specialized structures in the outside ectoderm. The possible relationship of these structures to osmoregulatory functions is considered in the Discussion"--P. 369.Item The sloughing of the melanic area of the dorsal fin, an ontogenetic process in Tylosurus raphidoma. Bulletin of the AMNH ; v. 99, article 1(New York : [American Museum of Natural History], 1952) Breder, Charles M. (Charles Marcus), 1897-; Rasquin, Priscilla."Small juvenile Tylosurus raphidoma (Ranzani) concomitantly develop elongation of the posterior rays of the dorsal fins and mandibular lappets. Both structures are areas of intense melanin concentration. 2. Larger juveniles and sexually mature adults lack both these features, having no mandibular lappets and possessing a dorsal fin which is high anteriorly and low posteriorly, and shows no concentration of melanophores at any place. 3. The metamorphosis from one form into the other is evidently rapid, for individuals in the state of transformation are not nearly so common as those above and below the size at which it occurs. 4. This transformation takes place when the fish are 200 mm. and 300 mm. in standard length and long before sexual maturity is attained which at the earliest is not under 600 mm.; therefore it is evidently not under the control of endocrine changes which take place at the attainment of sexual maturity. 5. The transformation takes place at an age of approximately six months, and sexual maturity is not attained until a year has passed. 6. Individuals in the transitional stage may be found in the summer and fall, most of the spawning evidently taking place in the first half of the year. 7. The black areas of the dorsal are reduced not by resorption but by a process of sloughing off. The melanophores break down first, the fin membranes then disintegrate, and finally the fin rays snap off at their articulations. 8. Before the destructive changes take place, the final form of the fin is foreshadowed by the shape of the melanic area of the juvenile fin. 9. A change in behavior takes place before the process of sloughing off occurs, the young juveniles associating with floating twigs or stems about their own size and general color. After they stop this association, the changes described take place, and from then on they avoid such objects and live freely in open water. 10. Histological examination of the mandibular lappets of Tylosurus and the barbels of Cypselurus showed that these structures are eliminated by a process of resorption. 11. The presence of large numbers of coarse granular eosinophiles in all these involuting structures may be associated either with parasitism or with the resorption process. 12. No taste buds were found to be present in either the belonid lappets or the exocoetid barbels which are evidently homologous, a condition apparently unique among teleost oral appendages"--P. 21.Item Studies in the control of pigment cells and light reactions in Recent teleost fishes. Part 1, Morphology of the pineal region, Part 2, Reactions of the pigmentary system to hormonal stimulation. Bulletin of the AMNH ; v. 115, article 1(New York : [American Museum of Natural History], 1958) Rasquin, Priscilla.pt. 1. "The histomorphology of the pineal area is described for 33 species of teleosts. The pineal organ is composed of an end-vesicle, a stalk, and a short pedicle, but variations in size and development of the vesicle and stalk create great differences in the morphology of the organ in different species. 2. In general, those species in which the pineal organ is exposed to light passing through transparent overlying tissues, or in which the pineal area can be exposed to light by concentration of pigment granules in over-lying chromatophores, show a specialization of the pineal organ. The end-vesicle in particular covers a wide area, spreading over parts of the forebrain and optic lobes, with the surface area of pineal cells greatly increased by invaginations and convolutions of the walls. Those species in which the pineal organ is deeply buried under many tissue layers are found to have a more simplified structure, with the vesicle limited to a simple sac. 3. Cytological study shows that the pineal is a complex organ probably having both sensory and secretary functions. Nerve endings seen near the pineal cells are connected with ganglion cells. Fibers from the ganglion cells progress down the walls of the stalk and enter the habenular commissure. Two types of epithelioid cells form the inner walls of the pineal vesicle and stalk, resting on a connective-tissue, basement membrane. These epithelioid or pineal cells either are sloughed off into the lumen, or parts of them are broken off into the lumen to form an apocrine secretion. 4. The apocrine secretion of the pineal can be delivered to the cerebrospinal fluid through the opening in the base of the stalk or pedicle that connects the lumen of the pineal stalk with the third ventricle of the diencephalon. 5. The pineal secretion in teleosts is composed, at least in part, of glycogen and glyco-protein. In some species, as Atherina stipes, the pineal cells accumulate glycogen during hours of darkness. The quantity of glycogen decreases during hours of light. 6. Intraperitoneal implantation of fresh Atherina pineals caused no observable effect on pigmentation in Cyprinodon. 7. Pinealectomy in Astyanax had no effect on pituitary, thyroid, or gonads and no observable effect on pigmentation. No significant changes in phototaxis were observed, owing perhaps to the dense pigmentation over the top of the head in this species. 8. Although no specific sensory cells were discovered in the teleost pineals, the behavior of fishes shows a sensory influence of this area of the brain. Other results of this report indicate that there is no evidence for an endocrine function of the secretion of the teleost pineal gland" -- pt. 2. "Thirty-five species of teleosts were injected with adrenalin or with intermedin or with both hormones at different times. 2. Fishes can be grouped in three categories according to the reaction of the melanophore system to adrenaline: (1) fishes in which adrenalin causes concentration of pigment granules within all the melanophores, (2) fishes in which only the internal melanophores show pigment concentration, and (3) fishes in which none of the melanophores is affected by adrenalin injection. 3. In some species, dermal melanophores are not concentrated by the effects of adrenalin injection but are responsive to the direct application of the hormone to the skin. 4. The lipophores respond to adrenalin either by dispersion or concentration of pigment granules, depending upon the species. 5. Leucophores respond to adrenalin injection by dispersion of guanin granules. 6. Dispersion of melanin granules in chromatophores as a response to intermedin was confined to Ameiurus, Gambusia, Astyanax, and Atherina among the species used for this report. All other species showed no reaction of melanophores to intermedin. 7. All species responded to intermedin by dispersion of lipophores. 8. Six mammalian anterior pituitary preparations were tested for their effects on the pigmentation of the fresh-water characin Astyanax mexicanus and the marine goby Bathygobius soporator. These hormones were FSH, LH, TSH, MSH, prolactin, and growth hormone. In addition, ACTH was used on Bathygobius. 9. MSH administration caused dispersion of melanin granules in the melanophores of Astyanax. No pigmentary reactions were noted in this species after injection of any other pituitary fractions. 10. Administration of all the anterior lobe preparations caused dispersion of pigment granules in the xanthophores of Bathygobius. No reaction was noted in the melanophores. 11. MSH was administered to eight other species with the following results: in fresh water, Ameiurus nebulosus, dispersion of melanophores; in sea water, Gambusia sp. and Atherina stipes, dispersion of melanophores; Cyprinodon baconi and Monacanthus ciliatus, no reaction; Gambusia sp., Lutianus apodus, Irideo bivitatta, and Chaetodon striatus, dispersion of xanthophores or erythrophores"--P. 64-65.