Camelid Female Anatomy - Anatomy & Physiology

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Ovary

• Located ~36 cm from the opening of the vulva but are subject to great variations depending on the physiological stage.
  • For example, during pregnancy they becomes more ventral and are pulled forward during the advancing stages thus making them very difficult to palpate.
• The left ovary is generally more cranio-ventral in postion than the right ovary.
• The ovary is attached to the broad ligament by a well-defined strong ligament which extends from the hilus of the ovary to the tip of the corresponding uterine horn.
• Both ovaries are enclosed within a fold of the mesosalpinx known as the ovarian bursa, the apex of this bursa forms a large circular orifice within which lies the fimbriae of the oviduct.
• Their general appearance and size varies according to the age and activity of the animal. ** In the prepubertal animals they have a smooth and glistening surface with several raised small vesicles (2 - 5 mm in diameter) throughout the surface which correspond to the follicles.
  • In anoestrous females the ovaries are oval or circular, flattened laterally and have an irregular surface due to many small follicles.
  • During the breeding season, mature follicles and current copora lutea (CL) project from the main contour of the ovary and give it a more lobular form.
    • This lobulation increases with increased number of previous ovulations or pregnancies and is due mainly to the presence of old corpora albicantia.

Ovarian Structures

• The ovary consists of two major parts
  • Cortex
  • Medulla
• Whole organ is enclosed by a tunica albuginea except in the area of the hilus.
• Follicular activity takes place in the cortex and ovulation can occur anywhere on this surface.
• However, as camelids are induced ovulators (only ovulate in response to mating) there is no cyclical appearance of a CL in non-mated females.
• Corpora lutea are only present in the ovaries of recently bred or pregnant females.

Follicles

• Follicular activity is dominated by 4 types of follicles
  • Small growing follicles
  • Mature follicles
  • Regressing follicles
  • Over-large, anovulatory follicles
• As the follicular waves overlap with each other, several generations of follicles may be present at the same time.
• The small growing follicles are visible on the surface of the ovary as small slightly raised vesicles measuring between 2 - 4 mm, whereas the mature pre-ovulatory follicle measures between 13 - 20 mm [19,20] and is spherical, turgid, with a thin clear translucent wall and protrudes markedly from the ovarian surface.
• The appearance of regressing follicles depends on the stage of regression.
  • At the start of regression the follicular wall becomes thick and opaque and the diameter decreases slowly until the follicle recedes into the ovary itself.
  • Large anovulatory follicles are present in about 50% of non-mated females and their size and appearance can be highly variable.
    • They vary in size from 25 - 60 mm and may have a thin or thick, opaque wall and contain either serous or haemorrhagic fluid with various amounts of fibrin.

Corpus Luteum

• Forms after ovulation, which occurs 24 - 48 hours after mating.
• The ovulating follicle collapses at ovulation and then the follicular cavity fills with blood to form a corpus haemorrhagicum.
• Luteinization of the corpus haemorrhagicum occurs within 4 - 5 days and gives rise to a corpus luteum.
• Regression of the CL occurs between 10 - 12 days after a sterile mating or just before parturition in the pregnant female.
• The corpus albicans, originating from the regression of the CL of pregnancy is hard, white or grey in colour and has no blood vessels on its surface. Corpora albicantia of different sizes (5 - 12 mm in diameter) can remain on the surface of the ovary of the female for a long time.

Oviduct

• Y-shaped Uterus
• Almost all pregnancies carried in the left Uterine Horn.
• Ova shed from the right ovary must migrate down the right Uterine Horn to the Uterine Body and up the left Uterine Horn in order to establish pregnancy.

Hymen

• Membrane 3-4cm thick
• Persists from embryonic development in maiden females.
• Tough to break down, some males may fail to achieve it.
  • Mating will stimulate ovulation and subsequent rejection of the male by the female but no pregnancy.
  • May require assistance to break the hymen of maiden females using a sterile-gloved finger.