The anterior tooth development of cattle presented for slaughter: an analysis of age,sex and breed

In a cross-sectional study, data from records of cattle slaughtered over a 1-year period at a large abattoir in South West England were analysed using an ordered category response model to investigate the inter-relationships between age, sex and breed on development of the permanent anterior (PA) teeth. Using the model, transition points at which there was a 50% probability of membership of each category of paired PA teeth were identified. Data from ∼60 000 animals were initially analysed for age and sex effect. The age transition was found to be ∼23 months moving from zero to two teeth; 30 months for two to four teeth; 37 months for four to six teeth and 42 months for six to eight teeth. Males were found to develop, on average, ∼22 days earlier than females across all stages. A reduced data set of ∼23 000 animals registered as pure-bred only was used to compare breed and type interactions and to investigate sex effects within the sub-categories. Breeds were grouped into dairy and beef-type and beef breeds split into native and continental. It was found that dairy-types moved through the transition points earlier than beef-types across all stages (interval varying between ∼8 and 12 weeks) and that collectively, native beef breeds moved through the transition points by up to 3 weeks earlier than the continental beef breeds. Interestingly, in contrast to beef animals, dairy females matured before dairy males. However, the magnitude of the difference between dairy females and males diminished at the later stages of development. Differences were found between breeds. Across the first three stages, Ayrshires and Guernseys developed between 3 and 6 weeks later than Friesian/Holsteins and Simmental, Limousin and Blonde Aquitaine 6 and 8 weeks later than Aberdeen Angus. Herefords, Charolais and South Devon developed later but by a smaller interval and Red Devon and Galloway showed the largest individual effect with transition delayed by 8 to 12 weeks.     

Microdissection studies of the structural alterations induced in rat kidneys by experimental postischemic acute renal failure

A unique opportunity presented itself for a morphologic study of experimental unilateral acute renal failure (ARF) in male rats. The ARF had been induced in the rats by temporary occlusion (1h) of the left renal artery. Twenty-nine rats were divided into subsets as follows: 2-3 h, 24 h, 1 week, 2, 4, 8, and 12 weeks following release of occlusion. Microdissection showed a heterogeneous population of abnormally structured proximal tubules in which the regressive lesions of tubular necrosis were combined with the progressive reaction of repair. The lesions demonstrated are reminiscent of those which have been described in ARF in the human and in experimental animals. Many proximal tubules in the 2- to 3-hour subset presented 1-3 disruptive lesions (DLs) while greater numbers of proximal tubules from the 24-hour group presented 1-5 DLs. Many proximal tubules presented no DLs, but nearly all from the 24-hour subset (97-100%) displayed a squamate appearance which paralleled and was caused by acute tubular necrosis. At 1 week, a dilated pars recta was common, but by this time, the squamate pattern had disappeared. Many casts were present. At 2 weeks, many fewer casts were present in proximal tubules and none were seen at 4, 8 or 12 weeks. The nephrons, particularly the proximal tubules, presented a variety of structural alterations at 2, 4, 8 and 12 weeks. Changes of special interest include (1) the presence of swan-necks; (2) a distinctive squamate appearance of the proximal tubules in the animals killed at 24 h; (3) a spiral, curled appearance caused by differential hyperplasia in animals at 4, 8 and 12 weeks, and (4) a tendency for ischemic lesions to involve all layers of the renal cortex.     

The effect of destroying the whisker follicles in mice on the sensory nerve, the thalamocortical radiation and cortical barrel development.

Electrolytic destruction of whisker follicles in mice on the day of birth has been found to cause degeneration in the sensory nerve fibres supplying the follicles. The severity of the degeneration has been assessed in animals between 2 and 20 days old by counting the total number of myelinated fibres in the maxillary nerves on both normal and lesioned sides. The degeneration is apparent after 2 days and by 20 days the nerve on the lesioned side contains only 38% of the normal fibre content. This degeneration has also been shown to involve the trigeminal root, central to the ganglion. In addition, the lesioning procedure modifies the terminations of thalamocortical fibres in the barrel region of the sensory cortex. These terminations are normally in clusters, each corresponding to a barrel, but, after lesioning the follicles, the terminals appear to be evenly distributed in layer IV and cortical barrel structures no longer develop. In postnatal mice, electrolytic destruction of whisker follicles had less effect upon maxillary nerve fibres and cortical barrels. The number of myelinated axons surviving until day 20 increased progressively with later lesioning to reach nearly 80% of the control level when lesions were made on day 10. Cortical barrels became secure earlier than the maxillary nerve, for a normal number of cortical barrels was present at day 12 when follicles were destroyed on day 4. The implications of these results for the formation of cortical barrels is discussed.     

Dianhydrodulcitol treatment of lymphocytic choriomeningitis virus infection in suckling mice.

Mice 2--4 days of age were pretreated with a single 5 mg/kg dose of dianhydrodulcitol (DAD) and later infected intracerebrally with lymphocytic choriomeningitis (LCM) virus. These animals had a lower mortality rate and died later than the untreated control animals. Thus DAD pretreatment prevented in part of the animals the development of lethal meningitis, the consequence of LCM virus infection, reducing the cellular immune response. This effect of DAD could equally be observed in animals infected at the age of 16--18 days and of 4 weeks.     

Distribution of 3H-proline within transseptal fibers of the rat following release of orthodontic forces

Maxillary right first molar teeth of rats were tipped mesially with an orthodontic appliance for 2 weeks (experimental group), 3H-proline was injected, and orthodontic forces were removed 6 hr later (time 0). The contralateral molar teeth of treated (internal control group) and age- and weight-matched untreated animals (external control group) were also studied. Diastemata were created between the molar teeth by the orthodontic appliance, and transseptal fibers between first and second (P less than 0.001) and second and third molars (P less than 0.005) were significantly lengthened as compared to external and internal controls at time 0. Diastemata between molar teeth were closed 5 days after removal of orthodontic force. Transseptal fibers adjacent to the source of the orthodontic force (mesial region) had the highest mean number of 3H-proline-labeled proteins at time 0 and at all times following removal of the force (P less than 0.001), and had the highest rate of labeled protein removal (P less than 0.001). Half-lives for removal of 3H-proline-labeled transseptal fiber proteins were significantly greater in mesial and distal regions and significantly less in middle regions of experimentals than in corresponding regions of external controls (P less than 0.001). These data suggest the following: 1) transseptal fibers adjust their length by rapid remodeling in regions experiencing a tensile force; 2) collagenous protein turnover within the middle third of the transseptal fibers is more rapid subsequent to release of orthodontic force than during normal physiologic drift, suggesting that this region adapts rapidly to changes in adjacent tooth position and that these fibers do not play a significant role in relapse of orthodontically relocated teeth; and 3) significant differences in turnover rates of 3H-proline-labeled transseptal ligament proteins of external and internal control quadrants suggest that tooth movement produces both local and systemic effects on collagenous protein metabolism.     

Nerve and muscle development in paralysé mutant mice

Nerve and muscle development was studied in paralysé mutant mice. The mutant phenotype is first recognizable 6-7 days after birth (PN 6-PN 7) as cessation of muscle growth and weakness and incoordination of movement. Mutant animals die between 2 and 3 weeks of age. Muscle fibers from paralysé mutants had a unimodal distribution of diameters and normal numbers and distributions of acetylcholine receptors. The only structural abnormality seen was a reduced extracellular space within muscle fascicles. Total muscle choline acetyltransferase activity was reduced compared with that of control muscles, indicating that synaptic terminal development was impaired. Light and electron microscopy showed that polyneuronal innervation was retained in mutant endplates, and the normal process of withdrawal of redundant innervation did not occur. The paralysé muscles reacted to experimental denervation with an increase in extrajunctional acetylcholine receptor numbers. Intramuscular axons failed to become myelinated in mutant animals, although sciatic nerve axons were myelinated with a normal myelin thickness/axon diameter ratio. Nodes of Ranvier were elongated and myelin lamellae in the paranodal regions were poorly fused. Sciatic nerves in mutant animals retained the neonatal unimodal distribution of axon diameters, whereas in control animals it became bimodal by 2 weeks of age. Our results are not consistent with a previous suggestion that paralysé mutant muscle endplates are progressively denervated. We conclude that the major expression of the paralysé mutant phenotype is an arrest in development of both nerve and muscle during the first week after birth. The paralysé mutant gene most likely is involved in the general support of development of many or all body tissues from 1 week of age. We found no regression of any aspect of differentiation, once achieved.     

Contributions of raphe-cortical and thalamocortical axons to the transient somatotopic pattern of serotonin immunoreactivity in rat cortex

Two experiments were carried out to evaluate the relative contributions of thalamocortical and raphe-cortical fibers to the transient somatotopically organized pattern of serotonin (5-HT) immunoreactivity that appears in the primary somatosensory cortex (SI) of rats during the first 2 weeks of life. In the first experiment, the specific 5-HT uptake inhibitors, fluoxetine and paroxetine, were administered systemically, animals were killed 3, 6, or 12 h later, and cortices evaluated for 5-HT immunoreactivity. Fluoxetine treatment had no appreciable effect on the density of 5-HT immunoreactivity in the cortex. Paroxetine treatment caused a reduction in 5-HT immunoreactivity which was maximal 6 h after administration. Examination of the cortices of these animals revealed a loss of very fine dust-like 5-HT immunoreactivity, but a vibrissae-related pattern remained visible in thicker fibers. In a second experiment, raphe-cortical fibers were destroyed by systemic administration of 5,7-dihydroxytryptamine on the day of birth. Six days after this manipulation, 5-HT was applied directly to the cortex in vivo and the animals were then killed and cortices processed to demonstrate 5-HT immunoreactivity. The cortices of these rats revealed a fine dust-like immunoreactivity organized in a somatotopic pattern, but only very few 5-HT-positive axons. The results of these experiments suggest that both raphe-cortical axons and thalamocortical fibers contribute to the patterned 5-HT immunoreactivity observed in SI of perinatal rats.     

Role of spermatogonia in the stage-synchronization of the seminiferous epithelium in vitamin-A-deficient rats

After 20-day-old rats are placed on a vitamin-A-deficient diet (VAD) for a period of 10 weeks, the seminiferous tubules are found to contain only Sertoli cells and a small number of spermatogonia and spermatocytes. Retinol administration to VAD rats reinitiates spermatogenesis, but a stage-synchronization of the seminiferous epithelium throughout the testis of these rats is observed. In order to determine which cell type is responsible for this synchronization, the germ cell population has been analyzed in whole mounts of seminiferous tubules dissected from the testes of rats submitted to the following treatments. Twenty-day-old rats received a VAD diet for 10 weeks and then were divided into three groups of six rats. In group 1, all animals were sacrificed immediately; in group 2, the rats were injected once with retinol and sacrificed 3 hr later; in group 3, the rats were injected once with retinol, placed on a retinol-containing diet for 7 days and 3 hr, and then sacrificed. Three rats from each group had one testis injected with 3H-thymidine 3 hr (groups 1 and 2) or 7 days and 3 hr (group 3) before sacrifice. Three normal adult rats (approximately 100 days old) served as controls. Labeled and unlabeled germinal cells were mapped and scored in isolated seminiferous tubules. In group 1, type A1 and type A0 spermatogonia as well as some preleptotene spermatocytes were present; type A2, A3, A4, In, and B spermatogonia were completely eliminated from the testis. Neither type A1 mitotic figures nor 3H-thymidine-labeled-type A1 nuclei were seen.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies on the toxic effect of cadmium in the rat. I. Testicular changes induced by a single subcutaneous injection of cadmium chloride.

Adult male rats of Wistar strain were subcutaneously injected with a single dose of 0.025 mM CdCl2/kg body weight. The autopsies were performed 2 and 12 weeks post cadmium injection. Experimental animals showed a normal gain of body weight while a marked lowering of the testes weight was observed. The lowering of testes weight of cadmium treated rats occured mainly due to the necrosis of seminiferous tubules, volume of which is markedly lower if compared to intact control rats. After 2 weeks of experiment a marked enlargement of the interstitial gland of the testis occured while after 12 weeks the gland is markedly lower if compared to control rats and to rats studied 2 weeks post cadmium injection. Histochemical reactions for lactic, succinic, alpha-glycerophosphate and 3beta-hydroxy steroid dehydrogenases, NADH tetrazolium reductase, acid phosphatase and nonspecific esterases showed for irreversible necrotic changes of seminiferous tubules of cadmium treated rats while the damage to interstitial gland is only temporary.     

Redistribution of Schwann cells at the developing PNS–CNS borderline. An ultrastructural and autoradiographic study on the S1 dorsal root of the cat

In order to test our hypothesis that myelin-forming Schwann cells early during development, after having been eliminated from their parent axons, colonize neighbouring unmyelinated axons, we studied the distribution of Schwann cells at the PNS–CNS border in the feline S1 dorsal spinal root during pre- and postnatal development using electron microscopy and autoradiography. Myelination of axons peripheral to the PNS–CNS border began about 1.5 weeks before birth. The adult distribution of one-third myelinated and two-thirds unmyelinated axons was noted 3 weeks after birth. Analysis based on to-scale reconstructions of axon and Schwann cell samples from the first 6 postnatal weeks gave the following results. 1) CNS tissue appeared in the proximal part of the root around birth and expanded peripherally during the first three postnatal weeks. (2) The number of Schwann cells associated with myelinated axons decreased. (3) The number of Schwann cells associated with unmyelinated axons increased. (4) The mitotic activity of the Schwann cells was low at birth and nil after the first postnatal weak. (5) Apoptotic cell units were virtually absent. (6) Aberrant Schwann cells, i.e. short and very short Schwann cells with distorted and degenerating myelin sheaths, were common. (7) The endoneurial space contained numerous Schwannoid cells i.e. solitary cells surrounded by a basal lamina. (8) Cytoplasmic contacts between unmyelinated axons and aberrant Schwann cells or Schwannoid cells were observed. We take these results to support our hypothesis.     

Altersabhängiges Lernen bei der Japanischen Wachtel (Coturnix coturnix japonica)1

The main question of our investigation is: Do there exist age-specific learning abilities in animals? 120 quails (Coturnix coturnix japonica) of 12 different age groups (between one day and 20 weeks) were tested in a combination apparatus by using two training methods. 60 quails were trained with decreasing (1), 60 other quails with increasing learning assistance (2). In each case the learning period lasted 5 days after which the animals were tested in a two-way choice apparatus and in a simple maze. Retention was tested 3 weeks later. -The 2 methods led to different results. In general the younger animals learnt better than the older ones when trained by method 1. No differences in learning performance between the 12 age groups were obtained by method 2.     

Structural remodelling of cardiomyocytes in the border zone of infarcted rabbit heart

Cardiomyocyte dedifferentiation, as detected in hibernating myocardium of chronic ischemic patients, is one of the characteristics seen at the border of myocardial infarcts in small and large animals. Our objectives were to study in detail the morphological changes occurring at the border zone of a rabbit myocardial infarction and its use as model for hibernating myocardium. Ligation of the left coronary artery (LAD) was performed on rabbit hearts and animals were sacrificed at 2, 4, 8 and 12 weeks post-infarction. These hearts together with a non-infarcted control heart were perfusion-fixed and tissue samples were embedded in epoxy resin. Hibernating cardiomyocytes were mainly distributed in the non-infarcted region adjacent to the border zone of infarcted myocardium but only in a limited number. In the border zone itself vacuolated cardiomyocytes surrounded by fibrotic tissue were frequently observed. Ultrastructural analysis of these vacuolated cells revealed the presence of a basal lamina inside the vacuoles adjacent to the surrounding membrane, the presence of pinocytotic vesicles and an association with cisternae of the sarcoplasmatic reticulum. Myocyte quantitative analyses revealed a gradual increase in vacuolar area/total cell area ratio and in collagen fibril deposition inside the vacuoles from 2 to 12 weeks post-infarction. Related to the remote zone, the increase in cell width of myocytes located in and adjacent to the border zone demonstrated cellular hypertrophy. These results indicate the occurrence of cardiomyocyte remodelling mechanisms in the border zone and adjacent regions of infarcted myocardium. It is suggested that the vacuoles represent plasma membrane invaginations and/or dilatations of T-tubular structures.     

Trypanosoma congolense: Natural and acquired resistance in the bovine

A total of 42 animals of various ages were infected with Trypanosoma congolense to investigate age resistance. Ten of eleven animals between 4 months and 1 year of age survived the infection without treatment. Two of eleven animals in the age range of 1 to 2 years also survived the infection whereas all 20 animals between 2 and 5 years of age died or needed treatment to survive. Young animals which needed no treatment to survive were refractive to challenge for at least 1 year after their last patent parasitemia. Older animals which required treatment to survive were also challenged at intervals after therapy. Three animals infected for 49 to 75 days before treatment were rechallenged 198 to 296 days later. Extensions in prepatent periods ranged from 5 to 13 days when compared to controls and the resulting infections were of a relapsing nature followed by self-cure. Effects of this disease on clinical parameters of previously infected animals were minimal. One animal infected for 196 days and rechallenged 501 days later had a prepatent period of 14 days as compared to 5 days for controls. This animal developed a brief relapsing infection followed by self-cure. Animals which were infected for periods of 41 to 77 days, received treatment, and were then rechallenged from 600 to 900 days later, showed some resistance to infection. Prepatent periods were extended from 1 to 3 days over those of control animals and although the resulting disease was severe, one of four animals self-cured without treatment. When animals which had self-cured primary challenges were rechallenged at periods up to 2 years later, they were completely refractory. When 12 animals which were presumed to be immune to syringe-passaged T. congolense were challenged by tsetse fly bite with the same strain of trypanosome, an appreciable immunity was evident. Five of twelve immune animals did not become patent while the other seven developed mild infections without severe clinical signs. All nine controls developed severe infections with eight requiring treatment to survive. When animals immune to the Trans-Mara I strain of T. congolense were challenged either by syringe or tsetse fly bite with a heterologous strain of T. congolense obtained from a different geographical area, no evidence of immunity was detected.     

Rho-associated kinase (ROCK) inhibitor, Y27632, promotes neurite outgrowth in PC12 cells in the absence of NGF

Neurotrophins support neuronal survival and axonal regeneration after injury. To test whether local expression of Neurotrophin-3 (NT-3) would elicit axonal regeneration we lesioned the corticospinal tract (CST) at the level of the hindbrain and measured the number of axons that would grow from the unlesioned CST to the contralateral side where NT-3 was over expressed at the lumbar level of the spinal cord. An adenoviral vector that carried the rat NT-3 gene and the NGF signal peptide driven by the EF1α promoter (Adv.EF-NT-3) was used. This model enabled us to test the effects of NT-3 on axonal regeneration without confounding injury processes. Biotinylated dextran amine (BDA) was injected into the rat cortex on unlesioned side to mark CST axons 10 days postlesion. Adenoviral vectors (1 × 10⁹ pfu, Adv.EF-NT-3 or Adv.EF-LacZ) were delivered to lumbar spinal cord by retrograde transport from the sciatic nerve 4 days later. Histological examination 3 weeks later revealed that more BDA-labelled axons had grown from the unlesioned CST to the denervated side at the lumbar level. Morphometric measurements showed that a significantly larger number of BDA-labelled CST axons ( p  < 0.001) were present in the animals that were treated with Adv.EF-NT-3 than those treated with Adv.EF-LacZ. These data demonstrate that local expression of NT-3 will support axonal regeneration in the injured spinal cord without adverse effects and suggest that gene delivery of neurotrophins may be an effective strategy for nervous system repair after injury.
Acknowledgements:   Funded by NIH Grant NS35280 and by Mission Connect of the TIRR Foundation.     

Antiviral antibodies are necessary for control of simian immunodeficiency virus replication

To better define the role of B cells in the control of pathogenic simian immunodeficiency virus (SIV) replication, six rhesus monkeys were depleted of B cells by intravenous infusion of rituximab (anti-CD20) 28 days and 7 days before intravaginal SIVmac239 inoculation and every 21 days thereafter until AIDS developed. Although the blood and tissues were similarly depleted of B cells, anti-SIV immunoglobulin G (IgG) antibody responses were completely blocked in only three of the six animals. In all six animals, levels of viral RNA (vRNA) in plasma peaked at 2 weeks and declined by 4 weeks postinoculation (PI). However, the three animals prevented from making an anti-SIV antibody response had significantly higher plasma vRNA levels through 12 weeks PI (P = 0.012). The remaining three B-cell-depleted animals made moderate anti-SIV IgG antibody responses, maintained moderate plasma SIV loads, and showed an expected rate of disease progression, surviving to 24 weeks PI without developing AIDS. In contrast, all three of the B-cell-depleted animals prevented from making anti-SIV IgG responses developed AIDS by 16 weeks PI (P = 0.0001). These observations indicate that antiviral antibody responses are critical in maintaining effective control of SIV replication at early time points postinfection.     

Development of the caudate nucleus of rats in postnatal ontogenesis and formation of cholinergic mediation in it]

Morphological maturation of the rat's caudate nucleus and formation of cholinergic system in it were studied in postnatal ontogenesis. Under investigation were newborn rats, 7, 14, 21 day old rats and adult animals. The growth and maturation of the caudate nucleys were most intesne during the first two postnatal weeks, it was somewhat descreased by the beginning of the third week and continued in later terms as well. The structure of dendrites and axons became complicated during the first two weeks, the axo-dendritic contacts being also formed. The neuron structure in 14 days old rats was similar to that of adult animals. The activity of acetylcholinesterase in the caudate nucleus of 7 and 14 days rats was not great. It sharply increased by the 17th day and reached the level of adults with 3 weeks after birth. Possible correlations of the morpho-chemical maturation of the caudate nucleus and formation of motor activity in rats is discussed.     

The distribution of peritubular matrix in human coronal dentin

Thin semi-serial ground sections of coronal dentin were examined radiographically. The bulk of the coronal dentin was characterized by the majority of the tubules having a distinct peritubular zone. With the exception of the tubules running from the tip of the cusp to the pulp cornu, the bulk of peritubular matrix forming the walls of the tubules was disposed eccentrically. The matrix was thicker on the cervical sides of the tubule than it was on the incisal sides. In a relatively narrow layer of the coronal dentin between the bulk of the dentin and the predentindentin border area the thickness of the peritubular matrix varied considerably. It was extremely narrow or absent in some tubules and reached its greatest thickness in others. The tubules in the predentin border area showed little or no evidence of peritubular matrix. The area of dentin beneath the central developmental groove differed somewhat from the bulk of the dentin. Many of the tubules at all levels of this area showed little radiographic evidence of peritubular matrix. Obliterated tubules were seen in some of the sections taken immediately above the predentin-dentin border area in the region of the pulp cornu and were always seen at the junction of the mantle dentin and the circumpulpal dentin beneath the central developmental groove.     

The autonomous innervation of the buffalo (Bubalus bubalis) testis. An immunohistochemical study

The innervation pattern in the buffalo testis was determined by using histochemical and immunohistochemical methods. Nerves were concentrated in the tunica albuginea and septula testis, and did not show an uniform distribution. The tunica albuginea at the lateral and medial sides and at the free border of the testis is most densely innervated than at the epididymal border. At the cranial pole thick nerve bundles were observed between albugineal vessels and muscle bundles. Rare parenchymal nerves were found in perivascular position between seminiferous tubules and their occurrence is confined to lobules at the cranial and caudal testicular poles. An intense NPY immunoreactivity occurred in nerve bundles and in solitary varicose fibres. Nerves were concentrated in the tunica albuginea at the lateral and medial side and at the free border of the testis, and in the lobules at the cranial and caudal testicular poles. Sub P immunoreactivity was occasionally detected in some thicker nerve bundles and solitary fibers, in the tunica albuginea and in the wall of blood vessels, showing a similar distribution but less intensity and density than NPY immunoreactivity. TH immunoreactivity stained nerve fibers in the buffalo testis with a distribution pattern similar to that obtained with general neuronal markers. The histochemical reaction for AchE was negative, so cholinergic fibers cannot be detected in the buffalo testis. The histochemical NADPHd reaction stained rare nitrergic nerve bundles and solitary fibers. The majority of NADPHd activity was confined to the vascular endothelium, and rarely to the interstitial Leydig cells, whereas the Sertoli and germ cells did not show any reaction.     

Effect of neonatal administration of norethynodrel-mestranol on the reproductive system of female mice

39 female mice were injected with 98.5 mg norethynodreland 1.5 mcg mestrand (ENOVID) at 5 days of age. Eyelid opening, an indication of general maturation was significantly advanced from 15 to 12 days. (p less than .001). Vaginal opening advanced from 38 days to 37 days (p less than .001). After puberal age, all treated animals had persistant vaginal cornification showing the classical syndrome of steroid induced sterility. At autopsy, mammary pads of all the treated animals showed a branched duct system with slender ends and almost no alveoli. Most of the control animals had frequent alveoli. Ovarian weight was reduced by 50 percent in treated animals (p less than .001). .001). No corpora lutea were found in treated animals.