THE MORPHOMETRIC AND TOPOGRAPHIC STUDY OF PIG'S STOMACH DEVELOPMENT BETWEEN THE 35^TH AND 1145^TH DAY OF GESTATION

Aleksander Chrószcz
Department of Anatomy and Histology, Wrocław Univesity of Environmental and Life Sciences, Poland

ABSTRACT

The investigations were carried out on 138 pig's foetuses, 68 male and 70 female. During the anatomical analysis, the precise location and developental rates were estimated. The stomach location was described according to sceletotophic, syntophic and holotophic methods. Whole investgated material was statistically analysied. The highest stomach growth rate was observed in the third and fourth age group. Sex and the uterus horn location have not significant influence on any parameter measured and calculated in foetal pig stomach description. The mean value of stomach length indicates the linear (isometric) growth rate according to subsequent age groups and it is twice larger than the average width and thickness of stomach in the same group. The mean value of the width / length index equals 55.82%. It indicates the medium – wide shape of stomach in foetal period in toto. The value of this index in subsequent age groups clearly describes the dynamic processes of the shape and size rates changes in development of pig's stomach between the 35^th and 114^th day of pregnancy.

Key words: pig, stomach prenatal life, morphometry.

INTRODUCTION

The development of domestic mammal stomach is the complex process [2,9,13,17]. Especially in ruminants, the development of complex stomach creates the great challenge for embryology [4,5,6,9,10,17,18]. The stomach rotation and other developmental processes occurring in prenatal life are well known [2,8,12,16]. Therefore the work is aiming on the second part of prenatal life, the foetal period. It is between the 35^th and 114^th day of gestation [12]. The similar studies were carried out on Cercopithecus aethiops by Stelmasiak et al. [20]. The accessible literature lacks of wider informations on the morphology and development of pig's stomach in foetal period. Some investigations were carried out in adult pigs [1,5,12,13,21]. Full development and function of the alimentary tract occurs the highest importance for the newborn acomodation in the postnatal environment [7,11,18,19,23,24].

MATERIAL AND METHODS

In these investigations were used 138 pig foetuses, 68 male and 70 female. Whole material was coming from 13 sows, between the 35^th – 114^th day of gestation (Table 1). All animals were breeding in standard husbandry and they are genetic homogenous [22].

Table. 1. The age group of investigated material

Age group	Days of gestation	Uterus	(n)	Uterus horn		Foetus sex		Foetus sex in uterus horn
								n
				n		n		L		P
				L	P	♀	♂	♀	♂	♀	♂
I	35	1	15	8	7	6	9	3	5	3	4
	Σ		15
II	55–61	2, 3, 4	9, 10, 8	13	14	15	12	8	5	7	7
	Σ		27
III	70–76	5, 6	7, 7	8	6	8	6	4	4	4	2
	Σ		14
IV	82–86	7, 8	10. 16	14	12	11	15	5	9	6	6
	Σ		26
V	92–97	9, 10, 11	10, 7, 7	11	13	15	9	8	3	7	6
	Σ		24
VI	107–114	12, 13	17, 15	18	14	15	17	8	10	7	7
	Σ		32
I – VI	total	n	138	72	66	70	68	36	36	34	32
		%	100	52.17	47.83	50.72	49.28	26.09	26.09	24.63	23.19

The foetus age was estimated on the base of methods introduced by Marrable [12] and Latshaw [9]. Whole investigated material was divided into six age groups [3]:

• 1^st group – the 35^th day of gestation

• 2^nd group – the 56^th – 61^st day of gestation

• 3^rd group – the 70^th – 76^th day of gestation

• 4^th group – the 82^nd – 86^th day of gestation

• 5^th group – the 92^nd – 97^th day of gestation

• 6^th group – the 107^th – 114^th day of gestation.

During the morphometric analysis, the volume of foetal stomach, the length of stomach, the width of stomach and the thickness of stomach (Fig. 1), the greater curvature length, the lesser curvature length, the diam of gastric openings was measured. Before the morphometry, the stomach volume was filled with gelatine – water solution thorough the small insicion in rigth flanck of abdominal wall. The sceletopy and syntopy of stomach was estimated (Fig. 2). The measures were conducted by an electronic slide caliper and repeated three times. All morphometric results were uesd as the mean value. The width / length index, thickness / length index, the thickness / width index and the curvatures index were calculated. The result interpretation was carried out according to the literature [20]. The results were displayed as diagrams (diagrams 1-3), tables (Tables 1-3) and Fig. 2. The author used NAV [14] and NEV [15] in the descriptive part of this work.

Fig. 1. The morphometric measurements of stomach

A – thickness of stomach B – length of stomach C – width of stomach

Fig. 2. The sceletotopy of stomach

Th – thoracic vertebra L – lumbar vertebra GAS – stomach I – VI – age group

Diagram 1. The correlation between the crown – rump lenght and the age group

Diagram 2. The correlation between the lenght of stomach, thickness of stomach and width of stomach according to the crown – rump length

Diagram 3. The correlation between the stomach indices and the age group

Table. 2. The stomach indices and stomach volume according to the age gruop

Age group	Width/length ind	Thichness/length ind	Thickness/width ind	Curvature ind	Stomach volume [ml]
I	43.3	34.68	81.91	24.69	0.2
II	55	63.08	114.6	19.45	0.3
III	53.49	53.46	99.93	7.52	3.4
IV	65.61	54.6	83.22	10.64	7.9
V	59.86	64.6	92.65	16.03	12.1
VI	56.94	59.83	105.1	14.57	16.4
I – VI	55.82	55.13	98.73	15.48	---

Table. 3. The skeletotopy of foetal stomach

Age group	Foetus quantity in uterus horn		Cardiac orifice	Pyloric orifice	Body of stomacht A	Body of stomach B	Ribs quantity
I	total	15	12 – 14	14 – L1	11 – 13	14 – 16	15 – 16
	right	7	12 – 14	14 –L1	11 – 13	14 – 16	15 – 16
	left	8	12 – 14	15 – L1	11 – 13	14 – 16	15 – 16
II	total	27	11 – 14	13 – L1	11 – 14	12 – L3	14 – 16
	right	14	11 – 14	13 – L1	11 – 14	13 – L1	15 – 16
	left	13	11 – 14	14 – L2	11 – 13	12 – L3	14 – 16
III	total	14	12 – 14	14 – L1	11 – 14	14 – L2	15 – 16
	right	6	12 – 13	14 – L1	11 – 13	15 – 16	15 – 16
	left	8	12 – 14	14 – L1	11 – 14	14 – L2	15 – 16
IV	total	26	11 – 14	12 – 15	10 – 13	14 – L1	14 – 16
	right	12	11 – 14	12 – 15	10 – 13	14 – 16	14 – 16
	left	14	11 – 14	14 – 16	11 – 13	15 – L1	15 – 16
V	total	24	11 – 14	13 – 15	11 – 13	14 – 16	15 – 16
	right	13	12 – 14	13 – 15	11 – 13	14 – 16	15 – 16
	left	11	11 – 14	13 – 15	11 – 13	14 – 16	15 – 16
VI	total	32	11 – 14	12 – 15	10 – 13	12 – L2	14 – 16
	right	14	11 – 14	12 – 15	10 – 13	13 – L2	14 – 16
	left	18	11 – 13	12 – 15	10 – 12	12 – L1	14 – 16
I – VI		138

RESULTS AND DISSCUSION

The prenatal life of domestic pig can be divided into two subsequent parts: embryonic period (12^th-35^th day of gestation) and foetal period (36^th-114^th day of gestation). According to the growth ratives of internal organs and long axis of the body, the foetal period consists of two phases: allometric (36^th-55^th day of gestation) and isometric (56^th-144^th day of gestation) period [12].

The crown – rump length (CRL), introduced by Latshaw [8], occurred the linear growth rate in all investigated period of prenatal life (diagram 1). The square correlation coefficient (R² = 0.98) allows to classify the CRL growth rate as isometric. It was also proved by other authors [13]. The increase of average the length of stomach, the average width of stomach and the average thickness of the stomach are strongly correlated with the increase of CRL (diagram 2). The average length of stomach indicates the constant isometric growth rate between 35^th and 114^th day of pregnancy. The average width and thickness of stomach were growing positively allometric. The growth rate was significantly higher in the first part of foetal period (under 15 cm CRL) and the values decrease in the second part (over 20 cm CRL) (diagram 2).

The average values of the width / length index (55.82%), the thickness / length index (55.13%) and the thickness / width index (98.73%) were presented in diagram 3 and Table 2. The mean values of the width and breadth of stomach were comparable and the mean value of the length of stomach was twice larger than the average width of stomach. The mean value of the width / length index allows to classify the stomach as medium – wide shaped in whole foetal period, according to the classification introduced by Stelmasiak et al. [20].

In the first age group, the average width / length index (43.29%) indicates the shape of stomach as narrow (diagram 4). The high positively allometric growth of liver and left kidney envelopes the relatively small stomach located in the center of abdominal cavity and they fill up whole space of the cranial and medial abdominal regions (Fig. 3). The same growth rates proved Marrable [12].

Diagram 4. The correlation between the width/length index and the age group

Fig. 3. The sceletotopy and syntopy of stomach

GAS – stomach HEP – liver REN – kidney Th – thoracic vertebra L – lumbar vertebra

In the second age group, the width / length index increases (55%) and the stomach shape becomes medium – wide (diagram 4). In the third age group, the width / length index equals 53.49%, but in next age group it increases rapidly to reach its maximal value (65.61%) (diagram 4). It allows to classify the stomach shape as wide. The syntophy and holotophy of stomach can be explained by the positively allometric growth of stomach and intestine loops, simultaneously to negatively allometric growth rate of liver and left kidney. These two organs (liver and kidney) 'give place' in order to the stomach accomodation to the limited space of abdominal cavity (Fig. 3). The muscular reinforcement of ventral body wall is near completion in 55^th day of gestation [12]. In this period of prenatal life, the caudal margin of liver is dislocated cranially and the stomach wall (among the greater curvature) reaches the internal surface of left abdominal wall (Fig. 2). The parietal surface of stomach adjoins the caudal surface of diaphragma. The stomach becomes sligthly bent shape and it is also indicated by the curvature index decrease (diagram 5). In the second age group, it occurres the most caudal location (3^rd lumbar vertebra) of the visceral surface of stomach (Table 2 and 3).

Diagram 5. The correlation between the curvature index and the age group

In the fifth (60.55%) and sixth (56.94%) age group, the mean value of the width / length index decrease slowly and the stomach shape becomes finally medium – wide (diagram 4). The visceral surface of stomach dislocates cranially in order to reach the last intercostal space, the average value of the width / length index decrease and the curvature index was significantly lower (diagram 5).

The average curvature index equals 15.48% in whole feotal period and can be interpreted as slightly bent stomach (diagram 5). It was also proved, the lesser curvature grows faster than the greater curvature in 1^st, 2^nd and 3^rd age group (diagram 6). The highest value of the curvature index (24.69%) was observed in the beginnig of foetal period and can be interpreted as sharply bent stomach. In two subsequent groups, the index value decreases in order to reach the lowest value (7.515%) in the third age group (diagram 5). It suggests the stomach becomes slowly slightly bent. In the fifth (16.03%) and sixth (14.57%) age group the curvature index increases one more time (diagram 5).

Diagram 6. The correlation between the cardia – left curvature dimension (red) and the cardia – right curvature dimension (black) according to the age group

The statistical analysis of gastric dimensions and indices proved the dynamic dislocation processes occurring in the foetal period, but accessible literature lacks of wider information and interpretation of these processes [12]. The width / length index as a relation between some stomach projective dimensions is a beter tool for the stomach shape discribtion than the curvature index.

The sceletotophy of stomach indicates no significant changes between the 35^th and 144^th day of gestation (Fig. 3). The sceletophy of stomach was presented in Table 3 and 4. Only in the first and the fifth age group, the most caudal located point of stomach occurres at level of the last thoracic vertebra. In other age groups, this point was never located caudally to the third lumbar vertebra.

Diagram 7. Correlation between the stomach volume and the age group

The stomach volume proved the positove allometric increase in whole foetal period and the correlation coefficient (R² = 0.91) proved the logarithmic curve of trend (diagram 7).

CONCLUSIONS

1. The highest stomach growth rate was observed in the third and fourth age group according to the morphometric investigation results.

2. Sex and the uterus horn location have not significant influence on any parameter measured and calculated in foetal pig stomach discribtion.

3. The mean value of stomach length indicates the linear (isometric) growth rate according to subsquqent age groups and it is twice larger than the average width and thickness of stomach in the same group.

4. The mean value of the width / length index equals 55.82% amd it indicates the medium – wide shape of stomach in foetal period in toto. The value of this index in subsequent age groups clearly descreibe the dynamic processes occurring in the foetal period.

ACKNOWLEDGEMENT

My works entitled: The innervation and arterial blood supply of pig's stomach in foetal period; The morphology, development and histometry of swine gastric wall in the foetal period; The morphometric and topographic study of pig's stomach development between the 35^th and 114^th day of gestation are the parts of the Inaugural Dissertation, entitled: The morphology and development of stomach in pig's prenatal period, promoted by Prof. dr hab. Norbert Pospieszny and reviewed by Prof. dr hab. Henryk Kobryń and Prof. dr hab. Tadeusz Kuder. I would like to thank Them for all remarks and help during preparing this work for printing.

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Accepted for print: 19.09.2008

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Aleksander Chrószcz
Department of Anatomy and Histology,
Wrocław Univesity of Environmental and Life Sciences, Poland
Kożuchowska 1/3, 51-421 Wrocław, Poland
Phone: 071/3205742

email: bjorn@onet.pl

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