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Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana)
Thesis (PhD)--University of Pretoria, 2012.
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University of Pretoria
2013
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| _version_ | 1867613626607599616 |
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| access_status_str | Open Access |
| author2 | Nothling, Johan O. |
| author_browse | Nothling, Johan O. |
| author_facet | Nothling, Johan O. |
| collection | Thesis |
| dc_rights_str_mv | © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2012. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27999 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:39:08.341Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27999 Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) Nothling, Johan O. Soley, John Thomson fjs@yoafrica.com Stansfield, Fiona Jane African elephant (Loxodonta africana) Ovarian follicular reserve UCTD Thesis (PhD)--University of Pretoria, 2012. The aim of this study was to define the ovarian follicular reserve of wild African elephants in terms of its type of small follicles (SF), its establishment and distribution throughout the ovaries, and the change in numbers of SF in the embryo and fetus as well as throughout prepubertal and adult life. The large elephant population in Zimbabwe provided the opportunity to collect ovaries from elephants culled for management reasons and hunted professionally. In total, gross morphological and histological studies were done on the gonadal ridges from 5 embryos (76–96 days post conception) and ovaries from 11 fetuses (4.8–22.2 months), 29 prepubertal females (2 months–10 years), 24 adult females (11–55 years) and 7 aged females (56–70 years). Specimens were fixed in 4% buffered formalin before a series of 25 ìm thick sections were cut and examined using stereological protocols to count SF numbers in each section and thereby calculate the follicle reserve of the whole ovary. Prior to counting SF numbers, their distribution throughout the ovary was studied and the repeatability of counts was validated. Numbers of SF were highest in mid-term fetuses, lower in fetuses during the second half of gestation, even lower in calves younger than 4½ years, whereas the numbers in calves aged 4½–9 years were significantly higher than those in younger calves, and similar to what they were in late-term fetuses. The numbers of SF were substantially and highly significantly lower in elephant 10–15 years in age compared to calves aged 4½9 years, suggesting a reduction around puberty. Thereafter the ovarian reserve fell steadily until depletion around the age of 70 years. During adult life the ovarian reserve was composed of early-primary (EP) and true-primary (TP) follicles. By 45 years of age only TP follicles remained although these enabled oestrous cyclical activity for many more years; of 7 sets of ovaries recovered from females aged 57–70 years, 6 showed evidence of cyclical activity or pregnancy within the preceding 6 years. The study shows that EP and TP form the follicular reserve from before birth until 45 years, with TP forming the reserve thereafter, which depletes in some old elephants and persists to maximum life span in others. Production Animal Studies unrestricted 2013-09-07T12:42:35Z 2012-09-27 2013-09-07T12:42:35Z 2012-09-07 2012-09-27 2012-09-17 Thesis Stansfield, FJ 2012, Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana), PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/27999 > D12/9/181/ag http://hdl.handle.net/2263/27999 http://upetd.up.ac.za/thesis/available/etd-09172012-183127/ © 2012 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | African elephant (Loxodonta africana) Ovarian follicular reserve UCTD Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title | Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title_full | Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title_fullStr | Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title_full_unstemmed | Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title_short | Ontogeny of the ovarian follicular reserve of the African elephant (Loxodonta africana) |
| title_sort | ontogeny of the ovarian follicular reserve of the african elephant loxodonta africana |
| topic | African elephant (Loxodonta africana) Ovarian follicular reserve UCTD |
| url | http://hdl.handle.net/2263/27999 http://upetd.up.ac.za/thesis/available/etd-09172012-183127/ |