A note on foetal growth and development of the giraffe <i>Giraffa camelopardalis giraffa</i>

Skinner, J. D.; Hall-Martin, A.J.

doi:10.1111/j.1469-7998.1975.tb05971.x

Cited by 26 publications

(11 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Blood pressure also depends on neck length. Systemic blood pressure at birth in a giraffe (= a body mass of 100kg; Skinner & Hall-Martin, 1975) is the same as in other mammals but as giraffe grow and their neck elongates it rises (Fig. 1C).…”

Section: Discussionmentioning

confidence: 72%

An allometric analysis of the giraffe cardiovascular system

Mitchell

Skinner

2009

Comparative Biochemistry and Physiology Part A: Molecular &

View full text Add to dashboard Cite

There has been co-evolution of a long neck and high blood pressure in giraffes. How the cardiovascular system (CVS) has adapted to produce a high blood pressure, and how it compares with other similar sized mammals largely is unknown. We have measured body mass and heart structure in 56 giraffes of both genders ranging in body mass from 18kg to 1500kg, and developed allometric equations that relate changes in heart dimensions to growth and to cardiovascular function. Predictions made from these equations match measurements made in giraffes. We have found that heart mass increases as body mass increases but it has a relative mass of 0.51±0.7% of body mass which is the same as that in other mammals. The left ventricular and interventricular walls are hypertrophied and their thicknesses are linearly related to neck length.Systemic blood pressure increases as body mass and neck length increase and is twice that of mammals of the same body mass. Cardiac output is the same as, but peripheral resistance double that predicted for similar sized mammals. We have concluded that increasing hydrostatic pressure of the column of blood during neck elongation results in cardiac hypertrophy and concurrent hypertrophy of arteriole walls raising peripheral resistance, with an increase in blood pressure following.

show abstract

Section: Discussionmentioning

confidence: 72%

An allometric analysis of the giraffe cardiovascular system

Mitchell

Skinner

2009

Comparative Biochemistry and Physiology Part A: Molecular &

View full text Add to dashboard Cite

show abstract

“…A similar phenomenon of an ontogenetically conserved pattern in the arteries supplying the brain has also been noted recently for giraffes; however, for giraffes, the ICA is absent from an early age [37], rather than persistent throughout life as in camelids. These developmental patterns are strikingly different, in spite of the fact that giraffids and camelids have long gestational periods (greater than 325 days; [70,71]) and face a similar cardiovascular burden owing to neck elongation. A paucity of data on anatomical variation, developmental timing and genetic signalling necessitates further studies to assess whether these patterns arise through macroevolutionary, physiological and/or environmental mechanisms.…”

Section: Resultsmentioning

confidence: 99%

Cranial arterial patterns of the alpaca (Camelidae:Vicugna pacos)

O’Brien¹

2017

R. Soc. open sci.

View full text Add to dashboard Cite

Artiodactyl cranial arterial patterns deviate significantly from the standard mammalian pattern, most notably in the possession of a structure called the carotid rete (CR)—a subdural arterial meshwork that is housed within the cavernous venous sinus, replacing the internal carotid artery (ICA). This relationship between the CR and the cavernous sinus facilitates a suite of unique physiologies, including selective brain cooling. The CR has been studied in a number of artiodactyls; however, to my knowledge, only a single study to date documents a subset of the cranial arteries of New World camelids (llamas, alpacas, vicugñas and guanacoes). This study is the first complete description of the cranial arteries of a New World camelid species, the alpaca (Vicugna pacos), and the first description of near-parturition cranial arterial morphology within New World camelids. This study finds that the carotid arterial system is conserved between developmental stages in the alpaca, and differs significantly from the pattern emphasized in other long-necked ruminant artiodactyls in that a patent, homologous ICA persists through the animal's life.

show abstract

“…Giraffes are considered nonseasonal breeders [10,11], with a short cycle of approximately 15 days [12] and a comparatively long gestation of 448-457 days [13,14]. In zoos, reproductive events in this species were successfully characterized by fecal [14][15][16][17] and urinary [12] progestin (P4) and/or estrogen measurements.…”

Section: Introductionmentioning

confidence: 99%

Ovarian Ultrasonography Correlated with Fecal Progestins and Estradiol During the Estrous Cycle and Early Pregnancy in Giraffes (Giraffa camelopardalis rothschildi)1

Hildebrandt

Pootoolal²,

Rich³

et al. 2009

Biology of Reproduction

View full text Add to dashboard Cite

Fecal and urinary progestin analyses have shown that giraffes express a short reproductive cycle, averaging 15 days, compared with other large ruminants. However, actual ovarian events have not been correlated with the hormonal pattern. In this study, mature cycling female Rothschild giraffes (Giraffa camelopardalis rothschildi) were repeatedly examined by transrectal ultrasonography to correlate ovarian function with changes in fecal progestin (fP4 [n(c) = 6]) and estradiol (fE2 [n(c) = 6]) and serum progestin (n(c) = 2) as measured by enzyme immunoassay. Five females became pregnant and were monitored during early gestation. In this study, we discovered that hormone values for fP4 in cycling giraffes do not correlate with the classic profile of follicular development, ovulation, and luteogenesis. The corpus luteum (CL) and the next dominant follicle were forming simultaneously. A mean +/- SD peak in fE2 of 254.92 +/- 194.76 ng/g and subsequent ovulation occurred as early as 1 day after the fall in fP4. In pregnant giraffes, the CL reached a diameter significantly larger (mean +/- SD, 41.02 +/- 2.70 mm; P = 0.0126) than that during the cycle (33.48 +/- 2.80 mm), while follicular activity and fluctuating fE2 were still present. With this research, we demonstrated that the progesterone profile typically used to characterize the ovarian cycle does not correlate with luteal development in the ovaries of this species. Furthermore, we conclude that the giraffe could have evolved a short reproductive cycle because of the almost parallel order of ovarian events.

show abstract

A note on foetal growth and development of the giraffe Giraffa camelopardalis giraffa

Cited by 26 publications

References 8 publications

An allometric analysis of the giraffe cardiovascular system

An allometric analysis of the giraffe cardiovascular system

Cranial arterial patterns of the alpaca (Camelidae:Vicugna pacos)

Ovarian Ultrasonography Correlated with Fecal Progestins and Estradiol During the Estrous Cycle and Early Pregnancy in Giraffes (Giraffa camelopardalis rothschildi)1

Contact Info

Product

Resources

About