Morphological evaluation of spermatogenesis in Lake Magadi tilapia (Alcolapia grahami): a fish living on the edge

Papah, M. B.; Kisia, S. M.; Ojoo, R. O.; Makanya, Andrew; Wood, C. M.; Kavembe, G. D.; Maina, J. N.; Johannsson, O. E.; Bergman, H. L.; Laurent, P.; Chevalier, C.; Bianchini, A.; Bianchini, L. F.; Onyango, D. W. (2013). Morphological evaluation of spermatogenesis in Lake Magadi tilapia (Alcolapia grahami): a fish living on the edge. Tissue and cell, 45(6), pp. 371-382. Churchill Livingstone 10.1016/j.tice.2013.06.004

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Spermatogenesis in Lake Magadi tilapia (Alcolapia grahami), a cichlid fish endemic to the highly alkaline and saline Lake Magadi in Kenya, was evaluated using light and transmission electron microscopy. Spermatogenesis, typified by its three major phases (spermatocytogenesis, meiosis and spermiogenesis), was demonstrated by the presence of maturational spermatogenic cells namely spermatogonia, spermatocytes, spermatids and spermatozoa. Primary spermatogonia, the largest of all the germ cells, underwent a series of mitotic divisions producing primary spermatocytes, which then entered two consecutive meiotic divisions to produce secondary spermatocytes and spermatids. Spermatids, in turn, passed through three structurally distinct developmental stages typical of type-I spermiogenesis to yield typical primitive anacrosomal spermatozoa of the externally fertilizing type (aquasperm). The spermatozoon of this fish exhibited a spheroidal head with the nucleus containing highly electron-dense chromatin globules, a midpiece containing ten ovoid mitochondria arranged in two rows and a flagellum formed by the typical 9 + 2 microtubule axoneme. In addition, the midpiece, with no cytoplasmic sheath, appeared to end blindly distally in a lobe-like pattern around the flagellum; a feature that was unique and considered adaptive for the spermatozoon of this species to the harsh external environment. These observations show that the testis of A. grahami often undergoes active spermatogenesis despite the harsh environmental conditions to which it is exposed on a daily basis within the lake. Further, the spermiogenic features and spermatozoal ultrastructure appear to be characteristic of Cichlidae and, therefore, may be of phylogenetic significance.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Topographical and Clinical Anatomy

UniBE Contributor:

Makanya, Andrew

Subjects:

500 Science > 570 Life sciences; biology

ISSN:

0040-8166

Publisher:

Churchill Livingstone

Language:

English

Submitter:

Andrew Makanya

Date Deposited:

25 Jun 2014 16:21

Last Modified:

01 Apr 2019 12:50

Publisher DOI:

10.1016/j.tice.2013.06.004

PubMed ID:

23916093

Uncontrolled Keywords:

Spermatogenesis, Spermatogenic cells, Alcolapia grahami, Cichlidaes

URI:

https://boris.unibe.ch/id/eprint/54043

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