Macro

ACTA VET. BRNO 2004, 73: 37–43

Follicular Population and Oestrogen Receptor Alpha in Ovary of the Bitch
R. DOLEÎEL1, R. KYLIÁNKOVÁ1, V. KUMMER2, J. MA·KOVÁ2,
P. STARÁ1, R. VITÁSEK1
1University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic; 2Veterinary Research Institute,

Brno, Czech Republic
Received October 27, 2003
Accepted February 11, 2004
Abstract
DoleÏel R.,R. Kyliánková, V. Kummer, J. Ma‰ková, P. Stará, R. Vitásek:
Follicular Population and Oestrogen Receptor Alpha in Ovary of the Bitch. Acta Vet. Brno 2004,
73: 37-43.
The objective of this study was to evaluate the follicular population on ovaries as related to the
phases of oestrous cycle and age in bitches. Several characteristics of follicular population on
ovaries in follicular (Group 1, n= 3), luteal (Group 2, n = 7) and anoestral (Group 3, n = 8) phases
of the oestrous cycle and in young (≤ 6 years, n = 12) and old (≥ 7 years, n = 6) bitches were
observed. The numbers and proportions of primary, secondary, tertiary and atretic follicles,
diameters of the follicles and oocytes and distribution of oestrogen receptor alpha in ovaries after
ovariectomy were evaluated.Microscopical examination of slices stained with haematoxylin-eosin
was performed in 50 mm2 of ovarian tissue in each animal and immunohistochemical detection of
oestrogen receptor alpha was performed using a monoclonal oestrogen receptor alpha antibody.
Average numbers of all follicles were found 567 (31% atretic), 449 (27% atretic) and 408 (37%
atretic) in the Group 1, 2 and 3, respectively.Proportions of primary, secondary and tertiary
follicles regardless of phase of the oestrous cycle as well as age of animals were 72.0%, 24.5% and
3.5%, respectively. Proportions of these follicles in various phases of the oestrous cycle as well as
in young and old animals were not different. Diameters of primary (40.2 ± 15.20 µm), secondary
(102.4 ± 36.60 µm) and tertiary (323.7 ± 95.84 µm) folliclesas well as diameters of oocytes in
secondary (80.7 ± 16.66 µm) and tertiary (105.8 ± 17.64 µm) follicles increased synchronously to
follicular development (p < 0.01). High intensity of nuclear oestrogen receptor alpha
immunostaining was found within surface epithelium, in primary follicles and in luteal cells.
Medium immunoreaction was seen in secondary follicles and low expression of oestrogenreceptor
alpha was in tertiary follicles. No immunoreaction of oestrogen receptor alpha was found in atretic
follicles. The results show similar characteristics of follicular population in various phases of the
oestrous cycle both in young and old bitches. Diameters of follicles as well as diameters of oocytes
increased and contrary to this oestrogen receptor alpha expression decreasedsynchronously to
follicle development. The study did not show an effect of oestrous cycle and age on proportions of
primary, secondary, tertiary and atretic follicles as well as oestrogen receptor alpha distribution on
ovaries of the bitch.
Follicle, atretic follicle, oestrogen receptor alpha, oestrous cycle, age, bitch

The morphological and functional properties of ovarian follicles representobjective of
the recent research in many species of animals because quantity and quality parameters of
the follicular population define potency in reproduction. In addition, deeper knowledge of
follicular development gives an opportunity to increase efficiency of biotechnological
methods in reproduction. However, there is a lack of data about follicular population in
bitches.
Ovaries innewborn mammals contain several tens or hundreds of thousands of primordial
follicles, which represent a pool from which they will be recruited for growth during
postnatal life (Baker 1972). About half a million of primordial and primary follicles are
present on ovaries of a newborn puppy. Ovarian follicles successively develop and are
Address for correspondence:
Doc. MVDr. Radovan DoleÏel, CSc....