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Thomas Library

Honors Thesis Archive

Author Jonathan Clinger
Title Ultrastructural Description of the Late Spermatid in Notophthalmus viridescens
Department Biology
Advisors Kevin Gribbins, Matthew Collier, and Jay Yoder
Year 2013
Honors Departmental Honors
Full Text View Thesis (885 KB) Note: This is a very large file; it may be easier to download the file to your computer and open it from there.
Abstract Much is known of the mature spermatozoa within the spermatheca of newts and other salamanders. Within newts few studies have focused on the spermatids and their comparison morphologically to that of the spermatozoa just prior to ejaculation. Thus, this data is the first of several subsequent studies that will concentrate on spermatid morphology within the Red-spotted Newt during and right after spermiogenesis. Six Notophthalamus viridescens were collected from a pond in Missouri during June, July, and August. Newts were sacrificed, reproductive tracts were dissected out, and the testis was fixed in trumps, and then worked up using standard protocols for light and electron microscopy. SEM of the spermatozoa provides morphological information that is congruent with what has previously been described for N. viridescens. TEM of mature spermatids within the cyst and outside of ruptured cysts also showed similar characteristics ultrastructurally to the mature spermatozoa from the spermatheca. The acrosome is mature within these spermatids and has the notch or acrosomal barb common in newts. Also, comparable to the sperm, the flagellum consists of an axial and marginal filament connected to the axoneme via the undulating membrane. Mitochondria are abundant within the mitochondrial region of the axial filament of the midpiece. Overall, as expected the mature spermatids within the testis are morphologically similar to the spermatozoa of the newt spermatheca. Future studies will continue to focus on changes to spermatids at the early stages of spermiogenesis and more detailed analysis of the acrosome within elongating spermatids.

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