Follicular Size Threshold for Ovulation Reassessed. Insights from Multiple Ovulating Dairy Cows.

In cattle, follicular deviation to dominance begins when the selected ovulatory follicle reaches a mean diameter of 8.5 mm. The dominant follicle acquires the capacity to ovulate when it reaches a diameter of about 10 mm.

Cervix-rectum temperature differential at the time of insemination is correlated with the potential for pregnancy in dairy cows.

This study sought to establish whether temperature gradients between the cervix, vagina, and rectum at and 7 days post-artificial insemination (AI) were associated with the incidence of pregnancy in lactating dairy cows (Experiment I; n = 90 ovulating cows) and to evaluate temperature gradient dynamics from the time of insemination to 7 days post-AI under heat stress conditions (Experiment II; n = 16 ovulating and 4 non-ovulating cows). In Experiment I, 39 cows (43.3%) became pregnant.

Twin Pregnancies in Dairy Cattle: Observations in a Large Herd of Holstein-Friesian Dairy Cows.

Multiple pregnancies have devastating consequences on the herd economy of dairy cattle. This observational study examines incidence patterns based on data from the ultrasonographic examination of 1130 multiple pregnancies in cows in their third lactation or more carrying twins (98.8%), triplets (1.

Temperature gradients in the mammalian ovary and genital tract: A clinical perspective.

Temperature within mammalian reproductive tissues is noted to be a key component of fertility, and significant gradients in temperature can be demonstrated deep within the abdomen shortly before ovulation. Indeed, in the absence of such gradients in the ovary and genital tract, the processes of ovulation and fertilisation are severely compromised. This review aims to assess literature produced during the last five decades regarding temperature gradients in the mammalian ovary and genital tract.

Evolutionary sequences in mammalian reproductive biology.

Broad biological aspects and accepted evolutionary sequences may offer useful guidance towards a comprehensive explanation of the function of mammalian ovaries and oviducts and their vital contribution to the events of fertilization. Cooling of the preovulatory follicles before ovulation may well have its roots in the primitive stages of external fertilization in which aggregates of oocytes are shed into freshwater.

Luteal activity following follicular drainage of subordinate follicles for twin pregnancy prevention in bi-ovular dairy cows.

Twin pregnancy is undesirable in dairy cattle. This study examines luteal activity following ultrasound-guided puncture and drainage of the smaller pre-ovulatory follicle at timed AI in cows with a pre-ovulatory follicle in each ovary. Luteal activity was determined through Doppler ultrasonography and plasma progesterone (P4) concentrations.

Pre-ovulatory follicular cooling correlates positively with the potential for pregnancy in dairy cows: Implications for human IVF.

Introduction: In rabbits, pigs, cows and humans, pre-ovulatory Graafian follicles may be more than 1.0 °C cooler than ovarian stroma and both these ovarian compartments are cooler than deep rectal temperatures. This study examines the effect of follicular cooling on the incidence of pregnancy in dairy cows.

Pre-ovulatory follicular temperature in bi-ovular cows.

In a previous study on monovular cows, follicles revealed a mean antral (follicular fluid) temperature 1.54°C cooler than rectal temperatures in ovulating cows, whereas no such temperature differences were detected in non-ovulating cows. The present study adds to our previous work, this time considering 24 bi-ovular cows (one follicle per ovary).

Seminal plasma modulates the immune-cytokine network in the porcine uterine tissue and pre-ovulatory follicles.

Evidence is emerging that the interaction between male seminal fluid and female tissues promotes fertility, pregnancy, and health of offspring. This includes the acceleration of ovulation in a species known as a spontaneous ovulator, the domestic pig. Earlier studies revealed that seminal plasma acts by a local mechanism in the female pig.

Whither human IVF? Fertilisable oocytes selected on the basis of follicular temperature.

Bearing in mind specific parallels between cow and human ovarian physiology, as noted in the manuscript, we have measured whether the temperature in a pre-ovulatory follicle is cooler than that in adjacent tissues. Using a novel approach not requiring anaesthetics or surgical procedures, we found that follicular fluid bathing cow oocytes shortly before ovulation is cooler than the neighbouring uterine surface and cooler than deep rectal temperature (the reference body temperature in cattle). By contrast, Graafian follicles of comparable size and ultrasonic image that do not subsequently ovulate do not have a reduced antral temperature.

The oviductal transcriptome is influenced by a local ovarian effect in the sow.

Background: Oviducts participate in fertilization and early embryo development, and they are influenced by systemic and local circulation. Local functional interplay between ovary, oviduct and uterus is important, as deduced from the previously observed differences in hormone concentrations, presence of sperm, or patterns of motility in the oviduct after unilateral ovariectomy (UO). However, the consequences of unilateral ovariectomy on the oviductal transcriptome remain unexplored.

Outstanding questions concerning sperm-epithelial binding in the mammalian oviduct.

Preovulatory binding of viable spermatozoa in the oviduct isthmus is widely accepted as a preliminary to fertilization, but details of physiological events associated with epithelial binding and release from binding are themselves little understood. Important questions include the potential number, distribution and stability of such sites in the caudal isthmus, whether multiple molecular forms of binding exist within a single-mated individual, and whether some sites are more favourable than others for the maintenance of preovulatory sperm viability. Also to be resolved is whether spermatozoa interact with the first available binding sites in the isthmus, whether spermatozoa from second or subsequent matings bind closer to the site of fertilization, and whether the first spermatozoa entering the oviduct are those that will be released first with impending ovulation.

Oviductal Transcriptome Is Modified after Insemination during Spontaneous Ovulation in the Sow.

Gene Expression Microarray technology was used to compare oviduct transcriptome between inseminated and non-inseminated pigs during spontaneous oestrus. We used an in vivo model approaching the study from a physiological point of view in which no hormonal treatment (animals were in natural oestrus) and no artificial sperm selection (selection was performed within the female genital) were imposed. It is therefore emphasised that no surgical introduction of spermatozoa and no insemination at a site other than the physiological one were used.

Considerations of viscosity in the preliminaries to mammalian fertilisation.

Migration of spermatozoa in the female genital tract will be strongly influenced by the viscosity of the fluids encountered, yet little systematic analysis has been given to such a consideration. This essay reviews the series of milieux confronting a fertilising sperm during its progression to the oviduct ampulla. Two groups are discussed, first those in which ejaculation is into the vagina, second those in which semen enters the uterus during a protracted mating.

Peritoneal fluid concentrations of progesterone in women are higher close to the corpus luteum compared with elsewhere in the abdominal cavity.

Objective: To investigate the potential role of peritoneal fluid activity for the local delivery of gonadal steroid hormones.

Design: Prospective clinical study.

Setting: University hospital.

Physiological routes from intra-uterine seminal contents to advancement of ovulation.

Whole boar semen or seminal plasma has been demonstrated to advance the time of ovulation in gilts. As a means of clarifying this influence, the contribution of uterine lymphatics and their white cell populations has been examined. After duct visualisation with Evan's blue, lymph was sampled from a mesometrial vessel in eight pre-ovulatory gilts whose uterine lumen was infused simultaneously with whole semen in one ligated horn and saline in the contralateral ligated horn.

Presence and significance of temperature gradients among different ovarian tissues.

After recalling male gonadal physiology in respect of tissue temperatures within the scrotal sac, and raising questions concerning abdominal testes, attention turned to mature Graafian follicles and ovarian stroma. Temperature gradients between such tissues were summarized for human, rabbit, pig, and cow, and generally fell in the range of 1.3-1.

The Fallopian tubes in domestic mammals: how vital is their physiological activity?

Set in an historical perspective, this essay examines diverse physiological aspects of Fallopian tube function in domestic animals and man. Microsurgical experiments are described that established the role of the isthmus in imposing a sperm gradient up to the site of fertilisation. Resection of the isthmus followed by reanastomosis of the remaining portions of the tube generated a high incidence of polyspermy in mated animals.