Evolutionary Morphology Of The Primary Male Reproductive System And Spermatozoa Of Goblin Spiders (Oonopidae; Araneae) Author Lipke, Elisabeth Author Michalik, Peter text Bulletin of the American Museum of Natural History 2015 2015-09-24 2015 396 1 72 http://www.bioone.org/doi/10.1206/906.1 journal article 7643 10.1206/906.1 15ad630f-eff2-451d-a5f8-22731ff53851 0003-0090 4612269 Opopaea apicalis SPERM TRANSFER FORM ( fig. 25 ): Large sperm transfer forms (.25 Mm), Fig. 38. Characteristics of spermiogenesis of Silhouettella loricatula . A : The AV is separated from the nucleus by distinct electron-dense plate. B : Higher magnifications reveal little granular material inside the subacrosomal space, in addition to the acrosomal filament. C: The manchette of microtubules and the NC indicate the actual dimensions of the nucleus. D : The NC runs in the periphery of the nucleus and contains the AF. E : While the nucleus elongates a small, droplike peN is formed, which disappears in further development. F : The very small implantation fossa contains only the two centrioles; the axoneme, which possesses the typical microtubular pattern, originates from the distal centriole (inset). composed of only a chromatin thread that is embedded in an electron-dense matrix and surrounded by a thin (, 70 nm ) homogeneous secretion sheath ( fig. 25A, B ). Spermatozoa ( fig. 25 ): Acrosomal complex: AV absent. AF absent. Nucleus: prcN condensed chromatin thread that is tightly screwed ( fig. 25C ). peN absent. NC inapplicable (due to missing AF). Axoneme: absent. Fig. 39. Characteristics of sperm and spermiogenesis of Stenoonops peckorum . A : The chromatin condenses irregularly in developing spermatids and appears fibrillar. B : A single-layered manchette of microtubules surrounds the nucleus. C : The IF is very small and contains only the two centrioles. D : During further development, the nucleus extremely elongates. E : The short peN is thin and flag shaped. F : The AF, which originates from the subacrosomal space, clearly ends before the base of the axoneme. G : At the end of spermiogenesis, the main sperm cell components coil. NOTES ON SPERMIOGENESIS ( fig. 25 ): The chromatin is highly condensed and appears threadlike ( fig. 25 C–E). Moreover, the chromatin thread is helically contorted. Some mitochondria are visible. At the end of spermiogenesis, the manchette of microtubules, which surround the developing nucleus ( fig. 25E ), disintegrates.