Orchestina

Lipke, Elisabeth & Michalik, Peter, 2015, Evolutionary Morphology Of The Primary Male Reproductive System And Spermatozoa Of Goblin Spiders (Oonopidae; Araneae), Bulletin of the American Museum of Natural History 2015 (396), pp. 1-72 : 46-48

Orchestina sp. 1 ( Chile)

SPERM TRANSFER FORM ( figs. 26 , 27 ): Long (.80 Mm), tubelike synspermia ( fig. 26 ),

comprising two sperm ( fig. 26 ) that are arranged consecutively to each other ( fig. 26 ). A thick electron-dense secretion sheath (, 800 nm) surrounds the sperm conjugates ( fig. 27 A–D). Sperm cell components are uncoiled ( fig. 26 ) and surrounded by a small amount of conspicuous electron-dense fibrils, mitochondria are present ( fig. 27B ).

SPERMATOZOA ( fig. 27 ): Acrosomal complex: AV small, cylindrical. AF originates from the subacrosomal space and extend into the nuclear canal. Nucleus: prcN tubelike and

elongated (,19.2 Mm) with deep implantation fossa that extends as far as the anterior pole of the nucleus and is filled with a distinct, electron-dense centriolar adjunct ( fig. 27C ). peN absent ( fig. 27E ). NC located in the periphery. Axoneme: short (,19.2 Mm); 9+3 microtubular pattern.

NOTES ON SPERMIOGENESIS ( fig. 28 ): Within the testis all stages of spermiogenesis are visible. A small, developing AV is attached to the cell membrane ( fig. 28A , inset) and extends toward the anterior pole of nucleus, from which it is separated by a distinct electron-dense plate ( fig. 28A ). The AF originates from the subacrosomal space. During development of the spermatids the chromatin condenses and appears fibrillar in midspermatids ( fig. 28 B–D). The deep implantation fossa of early and midspermatids is filled with numerous microfilaments ( fig. 28 C, D ) and few electron-dense secretions ( fig. 28C, D ) that form a distinct centriolar adjunct in late spermatids, which completely covers the proximal centriole ( fig. 28 E–G). In the periphery of the developing spermatids numerous looplike constrictions are visible ( fig. 28H inset), resulting in a fringed appearance of the latter ( fig. 28H, I ).

Figures

Fig. 26. Surface reconstruction of parts of the highly convoluted deferent ducts and sperm transfer forms of Orchestina sp. 1. (Chile), as based on serial light-microscopy images, illustrating the shape and arrangement of synspermia within the lumen of the deferent duct and the two fused sperm within one sperm conjugate. The axoneme is hypothetically reconstructed based on the presence of dense microtubular network within the cytoplasm of the sperm conjugate.

Fig. 27. Characteristics of synspermia of Orchestina sp. 1 (Chile). A: The synspermia are surrounded by a thin, electron-dense secretion sheath; a distinct cap is formed. B: The periphery of the membrane of syncytium is composed of several small constrictions. C: Sperm of one sperm conjugate are either located next to each other, or arranged in tandem position. D: The sperm cell components are not coiled and thus sprawled within the sperm conjugate. E: The two centrioles are arranged rectangularly.

Fig. 28. Characteristics of spermiogenesis of Orchestina sp. 1 (Chile). A: At the anterior pole of the nucleus a small AV is formed, which is separated from the nucleus by a distinct, electron-dense plate. The AF originates from the subacrosomal space (inset). B: The chromatin starts condensation around the IF, which extends nearly as far as the anterior pole of the nucleus. C: The deep IF that contains the two centrioles is stabilized with microfilaments. D: These microfilaments are arranged in parallel. E: The axoneme originates from the distal centriole, a peN is not developed. F: In late spermatids a distinct centriolar adjunct is present in the IF. G: In addition to the manchette of microtubules, several microtubules arrange around the nucleus in late spermatids. H: The periphery of the spermatids possesses numerous looplike constrictions, which are obvious in higher magnification in (inset). I: Finally, two sperm fuse entirely and form large synspermia, the cytoplasm of which further compresses, while the sperm conjugates elongate.