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| | #REDIRECT [[Paper - The early development of the cat (1924)]] |
| =The early development of the cat (''Felis domestica'')=
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| {{Historic Disclaimer}}
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| ==Introduction==
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| Our knowledge of the early development of the Cat, as indeed of the Carnivora in general, is singularly incomplete. Th. L. W. Bischoff, in his classical monograph ' Entwicklungs- geschichte des Hunde-Eies ' published in 1845, provided the first account of the development of a Carnivore from the unsegmented egg onwards and, considering the date of his work, his achievement was really a remarkable one. In addition to later embryonic stages, he described and figured a series of segmenting ova and blastocysts of the Dog, with such fidelity and accuracy that his account is, even today, of the greatest interest and value. He recognized and figured the germinal vesicle of the full-grown ovarian ovum and the refractive granules (' Dotter ') present in the cytoplasm of the latter. He observed the persistence of part of the discus proligerus round the unsegmented tubal egg, and noted its thick zona and the numerous sperm-heads imbedded in it. He figured the two-celled egg with what are evidently two polar bodies situated in the plane of cleavage. He described and figured the three-celled and four-celled stages, his figures of the latter showing quite accurately the characteristic cross- shaped arrangement of the blastomeres. He figured three later tubal eggs, said to be composed of eight, ten, and eighteen blastomeres respectively, and he also illustrated and described a series of morulae and blastocysts from the uterus. He recognized the delicate membranous wall of the blastocyst lying inside the zona and also ' den runden und gleichmassig dunkeln Fruchthof ', and since he found that the latter is situated in the former, he termed this vesicular stage ' die Keimblase '.
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| No further contribution to our knowledge of early Carnivore development appears to have been made until 1876. In that year E. A. Schafer (now Sir E. Sharpey Schafer) gave an account (45) of the structure of blastocysts of the Cat, possessing a bilaminar embryonal area, one-sixtieth of an inch (0-4 mm.) in diameter. In 1897 Bonnet (14), in his paper on the development of the Dog, described and figured (his figs. 1-3, Taf. 80-1) three eggs of the Cat, one unfertilized, a second with two pronuclei, and a third divided into nine blastomeres of unequal size. He obtained no early material of the Dog, and begins his description of the development with blastocysts 1-5x1-2 mm. in diameter.
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| In 1911 there appeared a valuable paper by R. van der Stricht (55) entitled ' Vitellogenese dans l'ovule de chatte '. This paper, as is indicated by the title, is primarily concerned with providing a detailed account of the growth of the ovarian ovum, including the process of vitellogenesis in the Cat, but it also includes most valuable chapters dealing with matura- tion, fertilization, and the early stages of cleavage, though the cleavage process is not followed in detail beyond the three- celled stage. It also contains important data relating to breeding habits, oestrus, and ovulation.
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| {{Footer}}
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| [[Category:Catl]][[Category:Hill]]
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