. Brimleyana. Zoology; Ecology; Natural history. Necturus Testis and Reproduction 63 myoid cells resemble, both in appearance and position, those present in the boundary wall of mammalian seminiferous tubules. Although the intervening stages of lobular development ( spermatocytes, spermatids) are no longer present in the testes of animals at this time, it would appear that development of the interlobular cells is arrested through all stages in which germ cells are present in the lobule. Following spermiation, however, the interlobular cells now become less elongated with rounded nuclei. El
. Brimleyana. Zoology; Ecology; Natural history. Necturus Testis and Reproduction 63 myoid cells resemble, both in appearance and position, those present in the boundary wall of mammalian seminiferous tubules. Although the intervening stages of lobular development ( spermatocytes, spermatids) are no longer present in the testes of animals at this time, it would appear that development of the interlobular cells is arrested through all stages in which germ cells are present in the lobule. Following spermiation, however, the interlobular cells now become less elongated with rounded nuclei. Electron microscope examination of these cells in N. maculosus has demonstrated that they now possess abundant organelles normally associated with active steroidogenesis (Pudney et al. 1983). The regressing portions of the lobules eventually become surrounded by fully differentiated Leydig cells, which in cross section form what has been termed the "epithelioid ring" (see Fig. 9) (Humphrey 1921). This region, which occupies the peripheral part of the testis, between the terminal segments of the immature lobules and the testicular capsule, constitutes the newly formed glandular tissue. In the caudal zone of the testis this finally becomes the glandular tissue proper, which is markedly increased in volume by further hypertrophy of the Leydig cells and complete regression of the lobular remnants. The glan- dular tissue also becomes highly vascular with groups of Leydig cells closely associated with numerous blood Fig. 7. Glandular tissue proper is composed of hypertrophied Leydig cells (arrowheads) and degenerating remnants of seminiferous lobules (arrows). X Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original North Carolina State Museum of Natural History. [Raleigh, NC : North Carolina Stat
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Keywords: ., bookcentury1900, booksubjectnaturalhistory, booksubjectzoology
