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6 July 2020 Histological Investigation of the Nile Crocodile (Crocodylus niloticus) Phallic Glans
Brandon C. Moore, Herman B. Groenewald, Jan G. Myburgh
Author Affiliations +
Abstract

The male crocodylian phallus, an intromittent organ, transfers sperm to the female cloaca during reproduction. During copulation, the distal phallic glans inflates via blood-filled spongiform tissues; it enlarges into an elaborate shape that directly interacts with the female urodeum—the cloacal chamber that contains the female reproductive tract openings. Alas, the specific mechanics of crocodylian insemination and gamete transfer remain unclear. To that end, we investigated the gross and cellular morphology of the Nile crocodile (Crocodylus niloticus) glans characterizing tissues types and structural morphologies to better predict how these male tissues may interact with those of the female. We tracked blood flow from the descending aorta to the phallic glans by way of sulcus spermaticus-adjacent blood vessels. Utilizing an artificial inflation technique, we documented how the glans tissue shape changes with increased hydrostatic pressure in spongiform tissues including increases in height and width and the enlargement of a cup-like distal lumen. Sectioning the glans, we traced the decrease in dense collective tissues and the proliferation of inflatable tissues moving from proximal to distal. Concomitant with the development of the inflatable glans, we identified elastin-rich tissues around the inflatable glans regions and the deep sulcus spermaticus semen conduit. Together, these observations demonstrated the dynamic nature of the tissues, where collagen fibers supply mechanical strength and elastin fibers provide resilience and recoil. We hypothesize how these glans characteristics may interact with female tissues during copulation to increase the chance of successful gamete transfer.

© 2020 Brazilian Society of Herpetology
Brandon C. Moore, Herman B. Groenewald, and Jan G. Myburgh "Histological Investigation of the Nile Crocodile (Crocodylus niloticus) Phallic Glans," South American Journal of Herpetology 16(1), 1-9, (6 July 2020). https://doi.org/10.2994/SAJH-D-18-00083.1
Received: 13 November 2018; Accepted: 25 February 2019; Published: 6 July 2020
KEYWORDS
cloaca
copulation
Crocodylian
elastin
inflation
penis
phallus
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