Reproductive tract of a male macropod
English: Title: The cyclopædia of anatomy and physiology Identifier: cyclopdiaofana03todd (find matches) Year: 1847 (1840s) Authors: Todd, Robert Bentley, 1809-1860 Subjects: Anatomy; Physiology; Zoology Publisher: London, Sherwood, Gilbert, and Piper Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: MARSUPIALIA. The tubuli testis are relatively smaller than in the Rodentia, but are similarly arranged, the corpus Highmorianum being near the surface and upper part, not at the centre, of the gland. The epididymis is large, and generally loosely attached to the teslis : in a small species of Kangaroo I found the connecting fold of serous membrane half an inch broad. The vasa de- ferentia pass from the globus minor along the infundibular muscular sheath formed by the cremaster as far as the abdominal ring, then bend downwards and backwards, and termi- nate below and external to the ureters, at the commencement of the urethra (a, fg. 135), on each side a longitudinal verumontanal ridge. There are no vesiculae seminales in any Mar- supial quadruped. Fig. 135. Text Appearing After Image: A, Hypslprymnus. B, rhascolarctus. C, Phascolomys. As the part of the urethral canal immediately succeeding the termination of the vasa defe- rentia is the analogue of the vagina, some mo- dification of this part might be anticipated in the male corresponding with the extraordinary form and developement which characterise the vagina in the female : accordingly we find that the combined prostatic and membranous or muscular tract of the urethra is proportionally longer and wider in the Marsupial than in any other Mammiferous quadrupeds (Jig- 135, 6). It swells out immediately beyond the neck of the bladder, and then gradually tapers to its junction with the spongy part of the urethra: it is not, however, divided like the vagina. Its walls are thick, formed of an external thin stratum of nearly transverse muscular fibres; and a thick glandular layer, the secretion of which exudes by innumerable pores upon the lining membrane of this part of the urethra. In a male Kangaroo I found that a glairy mucus followed compression of this musculo-prostatic tract of the urethra: the canal itself is here slightly dilated. Three pairs of Cowper's glands (c, c, c, fg. 135) pour their secretion into the bulbous part of the urethra : the upper or proximal pair are not half the size of the two other pairs in the Kangaroo, but are relatively larger in the Koala and other Marsupials: the two lower pairs are situated, one on each side the lateral division of the bulb of the urethra; their ducts meet and join, above this part, with the duct of the smaller gland : each gland is inclosed by a muscular capsule. The penis consists of a cavernous and a spongy portion, each of which commences by two distinct bodies. The separate origin of each late- ral half of the spongy body constitutes a double bulb of the urethra (e, e. Jig. 135), and the ' ac- celerator urina?,' as it is termed, undergoes a similar division into two separate muscles, each of which is appropriated to compress its par- ticular bulb. The two bulbous processes of the corpus spongiosum soon unite to surround the urethra, but again bifurcate to form a dou- ble glans penis in the multiparous Marsupials, in which most of the ova are impregnated in both ovaria, as the Phalangers, Perameles, Opossums, &c. (b,b,fg.l36). This modification of the opposite extre- mities of the corpus spongiosum, called ' bulb' and 'glans,' was detected by Cowper in his dissection of a male Opossum; and, in his account of the anatomy of that animal in the Philosophical Transactions for the year 1704, he says, " As the bulb of the urethra in man is framed for the use of the glans, to keep it sufficiently distended when required, so it seems it is necessary to have (wo of these bulbs, inclosed with their particular mus- cles in this animal, to maintain the turgescence of its double or forked glans when the penis is erected."—Vol. xxiv. p. 1585. The force of this ingenious,reasoning on the correlation of the bulb to the glans might seem to be invalidated by the fact that in the uniparous Marsupials, as the Kangaroo, the glans penis (f,fg. 135) is single, and yet the bulb double : Note About Images 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 work.